Is grass-fed beef healthier than grain-fed?

Is grass-fed beef healthier for us than grain-fed beef? I've seen these claims: it's lower in fat and calories, has more omega-3 fatty acids and vitamins, and is a good source of conjugated linoleic acid. - Diana, Houston

First a note about the terms grass-fed and grain-fed. As a rule, beef cattle are raised on mother's milk, then on pasture grass for the first couple years. After that, most grass-fed cattle keep on grazing, but grain-fed cattle are sent to a feedlot to stuff themselves for a couple months prior to slaughter, a process called "finishing." A high-grain diet lets cattle put on as much as a pound of meat per six pounds of feed consumed. Large feedlots now account for 75 percent of U.S. beef production.

All the worse for us, some think. Several studies show grass-finished beef not only has significantly less fat than grain-fed, it's also higher in certain fats considered beneficial. Omega-3 fatty acids, linked to the prevention of heart disease, arthritis, cancer, and possibly depression, are significantly higher in grass-fed beef. So are those conjugated linoleic acids you mentioned, which may help reduce cancer, heart disease, diabetes, and fat buildup. Grass-fed beef is also higher in carotenoids, a source of vitamin A, plus vitamin E and other antioxidants that help prevent cancer and coronary heart disease.

Grain-fed beef doesn't come off worse in every comparison. It scores better on monounsaturated fat (one of the good ones). And anyway beef overall is leaner than it was years ago.

So, is grass-fed beef better for you? I won't claim the difference is dramatic, but overall, given what we know, yes.

What about palatability? Researchers say cooked grass-fed beef contains compounds associated with a "green" smell, whereas those in grain-fed beef smell "soapy." But test results for taste, tenderness, and juiciness have been all over the place-the only thing that jumps out is that meat eaters seem to like what they're used to.

Grass-fed beef has two potential downsides: greenhouse gas emissions and price. Here we get into the delicate issue of bovine methane output or, for the uneducated, cow burps. (Yup-the main source is burps, not farts.) Methane is a major contributor to the greenhouse effect, and among the major producers of methane are cud eaters, including cows. The typical cow produces 200 to 400 quarts of methane a day.

A big advantage of grain finishing is that cattle get to the slaughterhouse sooner and thus produce less methane-just 13 percent of bovine greenhouse emissions are produced during the feedlot stage.

Don't expect that to be the last word, though. A couple years ago two scientists from the Humane Society (Koneswaran and Nierenberg, 2008) claimed raising beef cattle on grass produced 40 percent less greenhouse gases and consumed 85 percent less energy than the feedlot method to boot.

Not likely, said two scientists funded by the beef industry (Avery and Avery, also 2008). The grass-is-good claim was misleading, they said, because the feedlot beef used for comparison was Japanese Kobe beef, produced by pampered cattle that get fattened far more slowly than typical American grain-fed cows. The Averys calculated that because of the additional land required, producing the U.S. beef supply using only grass would release an extra 277 billion pounds of greenhouse gases per year.

Nonsense, the Humane Society scientists retorted. You need to figure in the emissions involved in transporting the feed, the greenhouse gases that get pulled out of the atmosphere by pastureland soil, and other esoteric factors I won't get into. Plus we shouldn't be eating so much meat anyway. If they ever get this settled, I'll let you know.

In the meantime, one thing nobody disputes is you'll pay a premium for grass-fed beef-a conservative estimate puts it at 16 percent. Some say grazing cattle in pasture is more humane than the feedlot method; if you agree (the evidence is mixed), perhaps you won't mind the extra expense. Or maybe you just prefer that grass-fed taste. But the health argument alone doesn't strike me as persuasive. For most Americans there's a simpler, cheaper way to eat healthy: eat less.